Non-contact interference fringes are produced when light reflecting from the back surface and other interfaces in a film structure produces artifacts in a silver halide emulsion layer of the film. If the emulsion layer is sufficiently turbid, light scattering can reduce these artifacts to the point of undetectability. However in films where the silver halide grain size is small and the exposing radiation is coherent as in, for example, image producing systems such as laser printers, non-contact interference fringes can seriously degrade the quality of the image not only from an aesthetic standpoint but also in a substantial loss of information cased by density distortions associated with the fringes.
To diminish the non-contact interference fringes in a photographic film, one may increase the turbidity of the emulsion layer by coating the silver halide at a higher concentration. However the increased silver level adds to the cost of the film and largely negates the advantage of using a fine grain emulsion.
Grzeskowiak et al., U.S. Pat. No. 4,711,838, the disclosures of which are incorporated herein by reference, describes several approaches purported to prevent the formation of non-contact interference fringes. For example, the photographic element may include a diffuse transmitting topcoat layer and/or a diffuse reflecting or absorbing backing layer. The diffusive properties of these topcoat and backing layers may be achieved by microscopic roughening of their surfaces or by including in them a binder and particles having a high refractive index, for example, desensitized silver halide. Alternatively, the photographic element may include a backing or subbing layer containing a dye that absorbs in the wavelength range of the exposing source.